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Study says failure rates 15 times that of what manufacturers indicate

A study released this week by Carnegie Mellon University revealed that hard drive manufacturers may be exaggerating their mean-time before failure (MTBF) ratings on hard drives. In fact, researchers at Carnegie indicated that on the average, failure rates were as high as 15 times the rated MTBFs.

Rounding-up roughly 100,000 hard drives across a variety of manufacturers, researchers at Carnegie tested the drives in various operating conditions as well as real world scenarios. Some drives were at Internet services providers, others at large data centers and some were at research labs. According to test results, the majority of the drives did not appear to be affected by their operating environment. In fact, researchers indicated that drive operating temperatures had little to no effect on failure rates -- a cool hard drive survived no longer than one running hot.

The types of drives used in the study ranged from Serial ATA drives, SCSI and even high-end fiber-channel (FC) drives. Typically, customers will be paying a much larger premium for SCSI and FC drives, which also happen to usually carry longer warranty periods and higher MTBF ratings.

Carnegie researchers found that these high-end drives did not outlast their mainstream counterparts:
In our data sets, the replacement rates of SATA disks are not worse than the replacement rates of SCSI or FC disks. This may indicate that disk-independent factors, such as operating conditions, usage and environmental factors affect replacement rates more than component specific factors.
According to the study, the number one cause of drive failures was simply age. The longer the drive has been in operation, the more likely it will fail. According to the study, drives tended to start showing signs of failure after roughly five to seven years of service, after which there was a significant increase in average failure rates (AFR). The failure rates of drives that failed in their first year of service or shorter was just as high as those after the seven year mark.

According to Carnegie researchers, manufacturer MTBF ratings are highly overrated. Take for example the Seagate Cheetah X15 series, which has a MTBF rating of 1.5 million hours. This equates to roughly over 171 years of constant service before problems. Carnegie's researchers said however that customers should expect a more reasonable 9 to 11 years. Interestingly, real world tests in the study showed a consistent average failure of about six years.

The average replacement rate of drives ranged from 2-percent to a whopping 13-percent annually, indicating that there is a need for manufacturers to reevaluate the way a MTBF rating is generated. Worst of all, these rates were for drives with MTBF ratings between 1 million and 1.5 million hours.

Garth Gibson, associate professor of computer science at Carnegie indicated that the study was proof that MTBFs are not a reliable way of measuring drive quality. "We had no evidence that SATA drives are less reliable than the SCSI or Fiber Channel drives," said Gibson.

Carnegie researchers concluded that backup measures are a necessity with critically important data, no matter what kind of hard drive is being used. It is interesting to note that even Google's own data centers use mainly SATA and PATA drives. At the current rate, it is only a matter of time before SATA will perform equal or better than SCSI and FC drives, offering the same reliability, and for much less money.


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RE: hmmm...
By Pirks on 3/12/2007 3:01:31 PM , Rating: 0
or (d) use a tool like SyncToy from Windows XP Power Toys to backup/mirror only important folders, that's even more convenient than mirror raid because SyncToy or similar folder sync tool 1) does not back up everything including tons of waste/temps/cookies/etc, it backs up only the important folders 2) allows for fast video editing and other disk intensive operations where you could copy from one disk to another which is MUCH faster that copying/muxing/videoediting on just one single drive. you can't do this sort of stuff with mirror raid. so SyncToy has benefits of both mirror and two separate disks for fast disk/video/etc operations


RE: hmmm...
By TomZ on 3/12/2007 3:28:48 PM , Rating: 2
I have a couple of problems specifically with SyncToy:

1. It doesn't synchronize files marked "read only" properly, because it refuses to overwrite RO files on the sync target

2. SyncToy, IIRC, won't delete files on the target that have been deleted from the source

Probably other sync utilities don't have this problem.

With mirroring, who cares if it duplicates temp files or not?

If performance is a must, then just have two drive pairs that are mirrored. Mirroring doesn't prohibit performance.

Your use of SyncToy is the same as my description of backup. The benefit of still using mirrored raid is that you still have backups (the redundant drive) in between your backup period. For example, suppose I run SyncToy, Winzip, or a Backup utility nightly, and I work all day on something, at I have a HDD failure at 4pm, then the days' work is basically lost since I can't restore it from a backup.

The other benefit of mirroring is the ability to continue to work even when one of your HDDs stops working. This helps your immediate productivity/convenience, and it also keeps you from having to reload the OS, drivers, and apps again. You just put in a new drive, and the RAID controller automatically synchronizes, usually in the background while you do other work.


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